t-PA, but not desmoteplase, induces plasmin-dependent opening of a blood-brain barrier model under normoxic and ischaemic conditions

• Published in: Brain research 2014-05, Vol.1565, p.63-73
• Main Authors: Freeman, Roxann, Niego, Be׳eri, R. Croucher, David, Pedersen, Lars O, Medcalf, Robert L
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blood-brain barrier; Blood-Brain Barrier - drug effects; Blood-Brain Barrier - metabolism; Brain - drug effects; Brain - metabolism; Cells, Cultured; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Desmoteplase; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Fibrinolytic Agents - pharmacology; Fundamental and applied biological sciences. Psychology; Glucose - metabolism; Humans; ICH; Medical sciences; Neurology; Oxygen - metabolism; Oxygen-glucose deprivation; Permeability; Plasmin; Plasminogen - pharmacology; Plasminogen Activators - pharmacology; Stroke; Tissue Plasminogen Activator - pharmacology; Tissue-type plasminogen activator; Vascular diseases and vascular malformations of the nervous system; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2014.03.027

Abstract Tissue-type plasminogen activator (t-PA) is the only thrombolytic treatment available for patients with acute ischaemic stroke. However, t-PA can increase permeability of the blood-brain barrier (BBB). Desmoteplase is a plasminogen activator derived from the common vampire bat, currently under clinical development for ischaemic stroke. We compared how t-PA and desmoteplase influenced BBB permeability using a human in vitro model where primary brain endothelial cells (BEC) and astrocytes are co-cultured on the opposite sides of a porous membrane. Permeability changes were evaluated 6 or 24 h post-stimulation by passage of fluorescent albumin across the membrane. Under normoxic conditions, t-PA, but not desmoteplase, increased BBB permeability. Surprisingly, the ability of t-PA to affect the barrier was lost under conditions of oxygen-glucose deprivation (OGD). Addition of plasminogen re-sensitised the BBB to the action of t-PA under both normoxia and OGD, but did not affect the inert behaviour of desmoteplase, even when digested fibrinogen was added to ensure optimal plasmin generation. These observations coincided with plasmin-dependent changes in astrocyte and BEC morphology and disruption of tight junction proteins in BECs, specifically initiated by t-PA but not by desmoteplase. Finally, inhibition of plasmin post-stimulation with t-PA and plasminogen, especially within 2 h, protected the BBB against t-PA-mediated barrier opening. Hence t-PA, but not desmoteplase, increases BBB permeability under both normoxic and OGD conditions in a reversible, plasmin-dependent process. The inability of desmoteplase to increase permeability despite its capacity to generate plasmin provides further support for its use as thrombolytic in patients with ischaemic stroke.